"There's a group of immune cells that essentially regulate the good and the bad bacteria and it's not been known how the body makes those cells," says lead author Associate Professor Gabrielle Belz, from the Walter and Eliza Hall Institute.

"We've been looking at one of those genes that is responsible for one of those cell types actually being generated and collectively protecting the gut from infections and bad bacteria."

Genetically-engineered mice with this particular gene 'knocked out' are much more susceptible to gut infections, she says.

The cells, called innate lymphoid cells (ILC), come in many different forms and serve a range of functions throughout the body. However in this case, the researchers focused on a particular type of innate lymphoid cell that produces a immune signalling protein called interleukin 22 (IL-22).

"IL22 is protective so it helps repair the epithelium [the cells lining the gut] and if the epithelium is intact then you tend not to get problems with differentiation that lead to cancer," says Belz.

"Whereas if those cells don't exist, it has been shown recently that it could lead to the development of cancer in a mouse model."

Greens and genes

Green leafy vegetables such as bok choi and broccoli contain a compound already known to indirectly trigger a receptor on the surface of innate lymphocytes. This new research suggests this compound could play a role in development and function of these cells.

"Proteins in these leafy greens could be part of some signaling pathway that is used by T-bet to produce ILCs," says Belz.

Understanding how these important gut immune cells are produced and what affects their production could help researchers to understand what happens when this system breaks down.

While the study was conducted in mice, it could have implications for human diseases that affect the gut, such as Crohn's disease, and even conditions such as obesity.

"It has been shown that the microbiome of the gut influences the ability to use nutrients properly and therefore obesity - at the moment there's an interesting network of links to the intestinal health of an animal, as regulated by these different cells types," Belz says.

"So people are starting to look at whether exactly the same sorts of arrangements are occurring in humans because potentially they could be a target of treatments."